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package com.fasterxml.jackson.databind.deser.std;

import java.io.IOException;

import com.fasterxml.jackson.core.JsonParser;

import com.fasterxml.jackson.databind.*;
import com.fasterxml.jackson.databind.deser.ContextualDeserializer;
import com.fasterxml.jackson.databind.deser.ResolvableDeserializer;
import com.fasterxml.jackson.databind.jsontype.TypeDeserializer;
import com.fasterxml.jackson.databind.util.ClassUtil;
import com.fasterxml.jackson.databind.util.Converter;

/**
 * Deserializer implementation where given Java type is first deserialized
 * by a standard Jackson deserializer into a delegate type; and then
 * this delegate type is converted using a configured
 * {@link Converter} into desired target type.
 * Common delegate types to use are {@link java.util.Map}
 * and {@link com.fasterxml.jackson.databind.JsonNode}.
 *

* Note that although types (delegate, target) may be related, they must not be same; trying * to do this will result in an exception. *

* Since 2.5 There is {@link StdNodeBasedDeserializer} that is a simplified version * for cases where intermediate type is {@link JsonNode} * * @param Target type to convert to, from delegate type * * @since 2.1 * * @see StdNodeBasedDeserializer * @see Converter */ public class StdDelegatingDeserializer extends StdDeserializer implements ContextualDeserializer, ResolvableDeserializer { private static final long serialVersionUID = 1L; /** * Converter that was used for creating {@link #_delegateDeserializer}. */ protected final Converter _converter; /** * Fully resolved delegate type, with generic information if any available. */ protected final JavaType _delegateType; /** * Underlying serializer for type T. */ protected final JsonDeserializer _delegateDeserializer; /* /********************************************************** /* Life-cycle /********************************************************** */ @SuppressWarnings("unchecked") public StdDelegatingDeserializer(Converter converter) { super(Object.class); _converter = (Converter)converter; _delegateType = null; _delegateDeserializer = null; } @SuppressWarnings("unchecked") public StdDelegatingDeserializer(Converter converter, JavaType delegateType, JsonDeserializer delegateDeserializer) { super(delegateType); _converter = converter; _delegateType = delegateType; _delegateDeserializer = (JsonDeserializer) delegateDeserializer; } /** * @since 2.5 */ protected StdDelegatingDeserializer(StdDelegatingDeserializer src) { super(src); _converter = src._converter; _delegateType = src._delegateType; _delegateDeserializer = src._delegateDeserializer; } /** * Method used for creating resolved contextual instances. Must be * overridden when sub-classing. */ protected StdDelegatingDeserializer withDelegate(Converter converter, JavaType delegateType, JsonDeserializer delegateDeserializer) { ClassUtil.verifyMustOverride(StdDelegatingDeserializer.class, this, "withDelegate"); return new StdDelegatingDeserializer(converter, delegateType, delegateDeserializer); } /* /********************************************************** /* Contextualization /********************************************************** */ // Note: unlikely to get called since most likely instances explicitly constructed; // if so, caller must ensure delegating deserializer is properly resolve()d. @Override public void resolve(DeserializationContext ctxt) throws JsonMappingException { if (_delegateDeserializer != null && _delegateDeserializer instanceof ResolvableDeserializer) { ((ResolvableDeserializer) _delegateDeserializer).resolve(ctxt); } } @Override public JsonDeserializer createContextual(DeserializationContext ctxt, BeanProperty property) throws JsonMappingException { // First: if already got deserializer to delegate to, contextualize it: if (_delegateDeserializer != null) { JsonDeserializer deser = ctxt.handleSecondaryContextualization(_delegateDeserializer, property, _delegateType); if (deser != _delegateDeserializer) { return withDelegate(_converter, _delegateType, deser); } return this; } // Otherwise: figure out what is the fully generic delegate type, then find deserializer JavaType delegateType = _converter.getInputType(ctxt.getTypeFactory()); return withDelegate(_converter, delegateType, ctxt.findContextualValueDeserializer(delegateType, property)); } /* /********************************************************** /* Accessors /********************************************************** */ @Override public JsonDeserializer getDelegatee() { return _delegateDeserializer; } @Override public Class handledType() { return _delegateDeserializer.handledType(); } @Override // since 2.9 public Boolean supportsUpdate(DeserializationConfig config) { return _delegateDeserializer.supportsUpdate(config); } /* /********************************************************** /* Serialization /********************************************************** */ @Override public T deserialize(JsonParser p, DeserializationContext ctxt) throws IOException { Object delegateValue = _delegateDeserializer.deserialize(p, ctxt); if (delegateValue == null) { return null; } return convertValue(delegateValue); } @Override public Object deserializeWithType(JsonParser p, DeserializationContext ctxt, TypeDeserializer typeDeserializer) throws IOException { /* 12-Apr-2016, tatu: As predicted, earlier handling does not work * (see [databind#1189] for details). There does not seem to be any compelling * way to combine polymorphic types, Converters, but the least sucky way * is probably to use Converter and ignore polymorphic type. Alternative * would be to try to change `TypeDeserializer` to accept `Converter` to * invoke... but that is more intrusive, yet not guaranteeing success. */ // method called up to 2.7.3: // Object delegateValue = _delegateDeserializer.deserializeWithType(p, ctxt, typeDeserializer); // method called since 2.7.4 Object delegateValue = _delegateDeserializer.deserialize(p, ctxt); if (delegateValue == null) { return null; } return convertValue(delegateValue); } @SuppressWarnings("unchecked") @Override public T deserialize(JsonParser p, DeserializationContext ctxt, Object intoValue) throws IOException { if (_delegateType.getRawClass().isAssignableFrom(intoValue.getClass())){ return (T) _delegateDeserializer.deserialize(p, ctxt, intoValue); } return (T) _handleIncompatibleUpdateValue(p, ctxt, intoValue); } /** * Overridable handler method called when {@link #deserialize(JsonParser, DeserializationContext, Object)} * has been called with a value that is not compatible with delegate value. * Since no conversion are expected for such "updateValue" case, this is normally not * an operation that can be permitted, and the default behavior is to throw exception. * Sub-classes may choose to try alternative approach if they have more information on * exact usage and constraints. * * @since 2.6 */ protected Object _handleIncompatibleUpdateValue(JsonParser p, DeserializationContext ctxt, Object intoValue) throws IOException { throw new UnsupportedOperationException(String.format ("Cannot update object of type %s (using deserializer for type %s)" +intoValue.getClass().getName(), _delegateType)); } /* /********************************************************** /* Overridable methods /********************************************************** */ /** * Method called to convert from "delegate value" (which was deserialized * from JSON using standard Jackson deserializer for delegate type) * into desired target type. *

* The default implementation uses configured {@link Converter} to do * conversion. * * @param delegateValue * * @return Result of conversion */ protected T convertValue(Object delegateValue) { return _converter.convert(delegateValue); } }